Save-the-dates are more than just a pre-wedding formality. They’re a chance to give guests a taste of what’s to come, and to properly introduce the soon-to-be-marrieds.

Thanks to social media, more and more engaged couples are using their save-the-dates as way to impress their guests and express their more creative side.

The best rule of save-the-dates is that there is no rule (well, other than being sure to include the couple’s names and the wedding date).

“You can go as far outside of the box as you can possibly think of going, or you can be very traditional with a postcard,” says Heather Long, founder and designer at Simply Designed, a stationery design company

Here are five of Harrison and Long’s favorite save-the-date ideas, based on things they’ve seen and designs they’ve worked on personally.

1. Food

Everyone loves a sweet treat, so what better way to whet an appetite for the wedding than with a customized cookie that’s “beautifully frosted to convey the couple’s message,” says Amber Harrison, style and trend expert for stationery company Wedding Paper Divas.

Inquire with local bakeries for the custom order. Also sites like Etsy have friendly bakers from all over who will make personalized cookie treats for your guests.

2. Printing on unique materials

“I had a client who wanted to print their save-the-dates on balloons because they were getting married in Disney World and their theme was the movie ‘Up,” says Long.

Personalizing an item that’s both representative of the couple and the wedding is a great way to have fun with the formality.

3. Embroidery

One of Harrison’s personal favorite designs she’s seen in recent years was an antique handkerchief embroidered with text. Another fun idea is embroidering vintage postcards with the couple’s name and date, or even T-shirts or hats.

4. Magnets

Magnets can offer a more traditional card look with a bonus feature: guests can’t forget the date if it’s constantly staring them down from the fridge.

Magnets allow plenty of room for customization. They can be straightforward engagement photos with text, text-only or even more cryptic. Check design websites like Minted.com for printing options.

5. Hone in on a hobby

Do you and your fiancé play a lot of board games? Read a lot of books? Watch a lot of “Game of Thrones?”

Shared affections are a great hook for guests to see how you really are as a couple. And working them into your save-the-date is easy. (Narrowing it down to just one interest is another story.)